1. Field of the Invention
The present invention relates to a COF board and, more particularly, to a COF board for mounting an electronic component.
2. Description of the Related Art
On a COF board, an electronic component such as a semiconductor element (an IC chip and the like) is nakedly mounted (bare-chip mounted) without being contained in a package by a COF (Chip on film) method. The COF board is mounted on various electronic equipment. The COF board typically includes an insulating base layer, and terminal portions formed thereon to be connected to the connection terminals of the electronic component.
As electronic equipment has been increasingly reduced in thickness, length, and width in recent years, a higher density has been required not only of an electronic component, but also of the terminal portions of a COF board.
To satisfy such a requirement, it is proposed that, e.g., terminal portions each including a shorter lead and a longer lead are formed at the end portions of belt-like conductors of a wired circuit board (see, e.g., Japanese Unexamined Patent No. 2005-183465). A plurality of the shorter leads extend in a direction in which the belt-like conductors extend, and are arranged in spaced-apart relation in a direction perpendicular to the extending direction thereof (widthwise direction). A plurality of the longer leads are arranged between the mutually adjacent shorter leads in spaced-apart relation in the widthwise direction. The terminal portions proposed in Japanese Unexamined Patent No. 2005-183465 are formed in an alternating and staggered arrangement (a two-row checker pattern), wherein the end portions of the shorter leads, and the end portions of the longer leads along the widthwise direction.